1. Technical Field
The present invention relates to intravenously-administrable immune globulin preparations. More specifically, the invention relates to immune serum globulin preparations that, aside from the immune globulin itself, are otherwise essentially protein free. The preparations are administrable by other routes as well. The preparations also are useful reagents for diagnostic testing and can be supplied in their solution form in diagnostic test kits.
The term immune globulin, also known as Immunoglobulin G, IgG and gamma globulin, encompasses both immune serum globulin and monoclonal immune globulins. Immune serum globulin is obtained from pooled plasma samples from either normal or hyperimmune donors and contains IgG antibodies to many common bacterial and viral infectious agents. Monoclonal immune globulins (monoclonal antibodies) are obtained from hybridomas.
Immune globulin long has been used in connection with the prophylaxis and treatment of a variety of diseases and disorders. Certain patients with immunodeficiencies are rendered susceptible to acute and chronic infections, with life-threatening consequences, which the immune system of the normal patient can easily combat. These patients with compromised immune systems are not able to produce normal levels of antibodies and can greatly benefit from the administration of exogenous immune globulin.
Patients with normal immune systems and antibody levels may require additional defense in overcoming certain antibiotic-resistant bacterial infections, such as those caused by Pseudomonas aeruainosa. Immunotherapy via the administration of immune globulin has become a standard treatment in these circumstances.
The administration of immune globulin is perhaps most widespread in the prophylaxis of what were once highly common diseases. Many viral infections, such as German measles, measles, mumps and smallpox, for example, can be controlled via the widespread administration of the appropriate immune globulins to children. The occurrence of many bacterial infections also have been controlled or virtually eliminated due to the widespread administration of immune globulins.
Immune serum globulins for human administration were first produced via an alcohol fractionation method developed by E. Cohn et al., J. Amer. Chem. Soc. 68: 459 (1946). These preparations contained approximately ten to eighteen (wt.) percent protein and were relatively stable during storage at 2 to 8.degree. C. Although originally intended for intravenous administration, it was found that untoward reactions, including anaphylactic shock, rendered unsafe such administration of the alcohol fractionated immune serum globulins. These products are acceptable for intra-muscular injection, however.
A particularly preferred method for producing an immune globulin fraction from Cohn Fractions I+II+III, for use in the present invention, is disclosed in U.S. Pat. No. 5,177,194 filed concurrently herewith and incorporated by reference herein.
Although intramuscular injection of immune globulin can effectively raise circulating antibody levels in most patients, this mode of administration suffers from several disadvantages. The antibodies administered in this manner diffuse rather slowly into the circulation. The ultimate blood levels attained from a given dose varies from patient to patient, and local tissue injury at the injection site is a possibility. Moreover, only a fraction of the total immune globulin administered to the patient reaches the bloodstream.
The intravenous administration of immune globulin overcomes these disadvantages. The desired level of circulating antibody is reached almost instantaneously and can be relatively accurately controlled by control of the dosage. Effectively larger doses can be more quickly administered without the discomfort associated with intramuscular injection.
As mentioned earlier, the intravenous injection of certain immune globulin preparations has lead to severe reactions. These reactions are generally believed to be caused by the activation of complement by aggregates and/or fragments of immunoglobulin which form during the preparation and/or storage of the immune globulin product. Thus, the safe administration of immune globulin requires steps to be taken to avoid the formation of immunoglobulin fragments and agglomerates and their resulting anticomplement activity.
Immune globulins (antibodies) also find wide use in the diagnostics field. Diagnostic test kits, intended for a single use, often contain a monoclonal antibody preparation as one of the test reagents. These antibody preparations are commonly provided in lyophilized form in order to increase their shelf life, and must be reconstituted just prior to use. The immune globulin preparations of the present invention, however, are quite stable and are well suited to being included in diagnostic test kits in their solution form.
2. Description of the Prior Art
The processing of immune globulin preparations in order to reduce anticomplement activity is documented in the literature. In "Preparation of a Stable Intravenous Gamma-Globulin: Process Design and Scale Up", Fernandes, P. M. and Lundblad, J. L., Vox Sang. 39: 101-112 (1980), the authors note that a variety of such processing methods have been investigated. The various techniques are (a) removal of high-molecular-weight aggregates by centrifugation, (b) pH adjustment to 4.0, (c) `gentle` fractionation techniques, (d) affinity methods, (e) use of protein stabilizers and (f) enzymatic treatment and other chemical modifications. None of these methods has been entirely successful from either the purely medical or commercial viewpoints, however. For example, the various chemical treatments can alter the immunoglobulin's physical structure and hence its activity. Some treatments for disassociating immunoglobulin agglomerates are not permanent; the agglomerates reappear during storage or during pH shifts to physiological conditions.
Japanese Kokai No. 60-146832 (1985) discloses that IgG preparations prepared via the cold ethanol fractionation and ammonium sulfate fractionation methods contain from 10 to 40 percent aggregated IgG in addition to 7S IgG. These preparations are unsuitable for intravenous administration because of their anticomplement activating effects. It is reported that these same preparations, after treatment by maintenance at pH 3.7 to 4.3 at 1 to 10.degree. C. over the course of 0.5 to 20 hours, no longer exhibit anticomplement activity. A stabilizing compound selected from among various inorganic salts, sugars, proteins and organic acid salts is added to prevent denaturation of the immunoglobulin chain during the acid treatment.
U.S. Pat. No. 4,719,290 (Curry et al.; Jan. 12, 1988) provides a reportedly intravenously-administrable gamma globulin preparation by stabilizing a purified Cohn Fraction II with relatively large amounts of human serum albumin. The final solution is formulated with the addition of sodium chloride and/or a carbohydrate.
U.S. Pat. No. 4,396,608 (Tenold et al.; Aug. 2, 1983) relates to a process for stabilizing immune serum globulin preparations so as to avoid aggregation. The pH of a Fraction II (or other Cohn fraction) filtrate is adjusted to 3.5-5.0 and the ionic strength is then adjusted (lowered) via filtration, dialysis, etc. or combinations thereof. The solution is then made isotonic via the addition of an amino acid, a carbohydrate or a sugar.
U.S. Pat. No. 4,093,606 (Coval; Jun. 6, 1978) relates to fractionation techniques whereby a suspension of Cohn Fraction II or II+III plasma protein is reportedly rendered stable for intravenous injection. Preparations are formulated with glycine, albumin and a non-ionic surfactant such as one of the polysorbates.
Although albumin is known for its ability to stabilize proteins in solution, its stabilizing properties diminish with time. Other factors also detract from the use of albumin. The presence of serum-derived albumin in a preparation may detract from its overall purity, as it is now well known that many contaminants, including proteins and infectious agents, can be neither easily detected nor removed with certainty in a cost effective manner. The presence of albumin also can mask the presence of immunoglobulin fragments in the immune serum. If such fragments are present, yet undetected, the presence of undesirable enzymes which produce such fragments also may go undetected. Thus, a need exists for improved stabilized immune globulin preparations which are albumin-free.